The present invention relates to a controlled type magnetic bearing device which suppresses the whirling or swing rotation due to the unbalance of a rotating body.
A magnetic bearing is a device which supports a rotating body by utilizing magnetic power. This type of bearing has been studied recently because of its excellent advantages that it is free of wear and fatigue. Magnetic bearings are used, for example, for a turbo-molecular pump, a centrifugal separator, a spindle for rotary machines, etc.
Since the rotating body is used as an element of the magnetic bearing in a magnetic bearing device, when the rotating body is not balanced, it provokes strong whirling, i.e., undergoes swing rotation about its axis of rotation, and causes the following troubles:
(1) Increase of oscillation and noise. PA0 (2) Increase of electric power loss on account of the increase of current to be supplied to the electromagnetic coil caused by the increase of whirling. PA0 (3) Decrease in machining performance because of an inaccuracy of rotation due to an unbalance caused by the mounted tool in the case where the magnetic bearing is used for a machining spindle. PA0 (4) Time required for correcting the unbalanced state.
As a result, the electric power circuit in the controlled type magnetic bearing device must be of relatively large scale.
The object of the present invention is to provide a controlled type magnetic bearing device which suppresses the whirling motion or swing rotation due to the unbalance of a rotating body supported by a controlled type magnetic bearing. The present invention is characterized by the arrangement of a static unbalance compensator and/or a dynamic unbalance compensator in a radial direction magnetic bearing device so as to lessen the whirling force caused by the unbalance state.